Category: Science

Night Time Light Exposure – Not a Bright Idea

We live in a very light polluted world in comparison to that of our very recent ancestors. Estimates now indicate that close to 99% of both Americans and Europeans are exposed to “light pollution.” Not only are we excessively exposed to light in modern times, but the type of light accounting for this exposure is changing rapidly. As we move away from incandescent lights in favor of light emitting diode (LED) technology, we are seeing an ever-increasing exposure to a particular part of the light spectrum – blue light, that has been associated with some worrisome effects in terms of human health.

New research shows that blue light exposure significantly reduces the amount of melatonin secreted by the brain’s pineal gland. This has obvious detrimental effects on both the duration as well as quality of sleep. Reduced quality of sleep has been associated with a number of issues including obesity, diabetes, and even Alzheimer’s disease.

In an interesting study, Spanish researchers evaluated 623 men with a diagnosis of prostate cancer and compared them to 879 male controls. Exposure to light from indoor sources at night was computed using a questionnaire, while outside exposure was calculated using data from the International Space Station. The latter data specifically allowed for the collection of information related to blue light exposure.

The study was carried out as it is known that light exposure may significantly alter hormone activity, and prostate cancer is a hormone related event. Further, previous research has demonstrated that night shift workers are known to have an increased of prostate cancer.

The researchers found that comparing those with the highest exposure to blue light to those with the lowest, the risk of prostate cancer was more than doubled. The risk was almost tripled in men who had high levels of light in their rooms when they slept in comparison to men who slept in “total darkness.”

So this is yet another argument in favor of considering the doctrine of the “paleo” movement. That is, there are health benefits associated with trying to emulate the environments of our ancestors. In this case, keeping in mind that when the sun went down, our ancestors were pretty much in the dark. And this history is recapitulated in our genetic code.

The important points here are that first, we should dramatically reduce our exposure to light as we approach and engage sleep. And the second, but nonetheless equally important point is that blue light, the kind emitted by our phones, computer screens and tablets, seems to be particularly disruptive of hormone activity and, according to this research, may well enhance the risk of prostate cancer.